Hydraulic system for fabricating dies



Jan. 16, 1962 F. M. WILLIAMSON ,707

HYDRAULIC SYSTEM FOR FABRICATING DIES Filed Feb. 12, 1960 3 Sheets-Sheet 1 PRESSURE 2 TANK INVENTOR.

Jan. 16, 1962 F. M. WILLIAMSON 3,016,707

HYDRAULIC SYSTEM FOR FABRICATING DIES Filed Feb. 12, 1960 3 Sheets-Sheet 2 I pzzssuze PRESS l TANK RAM a I I )4 3 2. 3 3 /d4 04 j/L/j x; 1 54 4. ATMOSPHERIC j /72 I I $1M l w I CYLINDER l1 L F'iog d )flf'PZrk/ysam BY A V WW flTTaK/VAWS,

Jan. 16, 1962 F. M. WILLIAMSON 3,016,707

HYDRAULIC SYSTEM FOR FABRICATING DIES Filed Feb. 12. 1960 3 Sheets-Sheet 5 ATMOSPHERIC F RT INVENTOR. 7%;1 fif/ Z'Z Z 114/7750:

Pifiliififl? Patented Jan. 16, 1962 3,016,707 HYDRAULEC SYSTEM FOR FABRICATING DIES Floyd M. Williamson, 452 Lakewood, Detroit 15, Mich. Filed Feb. 12, 196th Ser. No. 8,459 22 Claims. ((Il. 66-51) This invention relates to hydraulic systems for actuating fabricating dies and has particular reference to a system associated with a ram type press where the slides or punches operate on a different plane than the press ram or at a remote location.

Where a long stroke of the slide or punch is needed to aliow for loading or removal of the work and the volume of hydraulic fluid needed to advance the slide is large, very large master cylinders are conventionally required to provide enough fluid for actuating the punch or slide, although high pressure is not required over the full length of the stroke. My invention contemplates a hydraulic system wherein oil at low pressure is utilized to advance the slide during the initial major portion of the stroke and high pressure oil is developed upon the closing of the press ram to eifect the final portion of the work stroke. The system herein disclosed affords certain advantages over the system disclosed in my prior copending application Serial No. 832,720, filed August 10, 1959, for Hydraulically Actuated Piercing Unit, which is a continuation-in-part of my abandoned application Serial No. 788,544, filed January 23, 1959, for Hydraulically Actuated Piercing Unit.

A principal object of the invention therefore is to provide a hydraulic system for actuating fabricating dies which is particularly adapted for actuating long stroke punches or slides of fabricating dies where the slides or punches operate on a difierent plane than the ram or at a remote location.

Another object of the invention is to provide a hydraulic system in combination with a press type ram wherein hydraulic fluid at low pressure is utilized to advance the slide or punch during the initial part of the stroke and wherein high pressure developed by and upon closing of the press ram is employed to effect the fina portion of the work stroke.

Other and further objects of the invention will be apparent from the following description and claims and may be understood by reference to the accompanying drawings of which there are three sheets, which by way of illustration show preferred embodiments of the invention and what I now consider to be the best mode of applying the principles thereof. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.

FIG. 1 is a schematic illustration of a hydraulic system embodying my invention;

FIG. 2 is a schematic illustration of a modified form of control for the system illustrated in FIGS. 1 and 3;

FIG. 3 is a view similar to FIG. 1 but showing a modified form of the invention; and

FIG. 4 is a view illustrating a further modification.

As shown in FIG. 1, a hydraulic work cylinder having a piston 12 therein is provided with a piston rod 14. The rod 14 projects from one end of the cylinder 19 and reacts on a slide 16 of a fabricating die to effect the working stroke thereof upon the advance of the piston 12 in the cylinder 10. A tank 2% of hydraulic fluid maintained under pressure by air supplied through air line 2?. is connected by a fluid-low connection 22 to one end of the cylinder 10 whereby hydraulic fluid under the pressure (for example, 169 lbs. per square inch) to which it is subjected in the tank is supplied from the tank 2t to the cylinder to to advance the piston 12 therein I through the initial portion of the work stroke thereof. The connection 22 includes conduit 24 connected to the bottom of the tank 24 conduit 26, valve 23, conduit 39, conduit 32, conduit 34, valve 36, and conduit 3% which extends from valve 36 to one end of the cylinder 19.

The valve 28 includes a pressure relief valve 4-9 and a bypass 42 having check valve 44 therein. The other end of the cylinder 10 is connected by a fluid-flow connection 46 with the tank 20 for returning to the tank 2t fluid displaced from one end of the cylinder 16 as the piston 12 advances therein. The connection 46 includes conduit 48 extending from cylinder 10 to valve 36, conduit 51} in the valve 36, and passage 52 in the valve 36 to which the end of the conduit 24 is connected. A check valve 54 is arranged between the conduits 50 and 52 so as to permit free flow of fluid from the conduit 5% into the conduit 52 and to prevent reverse flow.

A hydraulic pressure cylinder 53 mounted on the bolster 60 of a reciprocating ram type press is provided with a piston 62 positioned to be engaged and advanced by the press ram 64 upon the closing thereof. A oneway fluid flow connection 66 extends from the tank Zii to the cylinder 58 whereby hydraulic fluid from the tank 20 and under the pressure in the tank is supplied from the tank to the cylinder 58 to retract the piston 62-that is, to bias it upwardly toward the press ram 64. The oneway connection 66 includes a part of the conduit 32, the conduit 30, valve 28, conduit 26, and a part of the conduit 24.

Pressure relief valve 40 is normally closed and normally prevents fluid flow from the conduit 30 through the valve 28 to the conduit 26, while free flow in the opposite direction is permitted through the bypass 42. The valve indicated generally at 23 preferably is of the construction disclosed and claimed in my Patent No. 2,901,238, issued August 25, 1959, for Circulating Systerns for Hydraulic Liquid Between Tanks and Cylinders. The valve 28 separates the low pressure side of the systemthat is, the side freely communicating with the tank 2tP-from the other or high pressure side, although much of the time the entire system is under only the pressure prevailing in tank 20. When excess pressure deveiops in the high pressure side of the system (such as when piston 12 is fully advanced before the press ram closes), the valve 40 will unseat and bleed oif suflicient fluid to the low pressure side of the system so as to dissipate the excess pressure on the high pressure side of the system.

A fluidflo-w connection comprising the conduits 32 and 34, valve 36, and conduit 38 extends between the pre sure cylinder 58 and the working cylinder it whereby hydraulic fluid discharged from the pressure cylinder 58 upon the advance of the piston 62 therein due to the closing of the press ram 64 is supplied at high pressure to the work cylinder It) to advance the piston 12 therein through the final portion of the work stroke thereof so as to actuate the punch or die upon which the slide 16 reacts.

A one-way fluid-flow connection extends from the bottom of the tank 20 to the hydraulic cylinder of an air pressure operated booster or reciprocating piston pump 72 and such connection includes the conduit 24, conduit 52 in the valve 36, conduit 74, and passages 76, 78 and 80 in the pump 72, the passage 8% communicating with the discharge end of the pump cylinder '70 in which the piston 82 is reciprocable. A check valve 34 between the passages 76 and 78 permits free flow from the passage 76 into the passage 78 and prevents return flow. The one way connection just described permits the pump cylinder 70 to be charged with oil from the tank 21} when the air cylinder 86 of the pump 7'2 is ported to atmosphere as shown. The conduit 32 extends into the cylinder head 88 of the pump 72, and check valve 99 is arranged between passage '73 and conduit 32 so as to permit hydraulic fluid discharged from the pump cylinder 70 to flow freely from the passage 78 into the conduit 32 but to prevent flow of fluid in a reverse direction.

A one-way fluid flow connection extends from the pump cylinder 70 to the work cylinder for supplying the hydraulic fluid to the cylinder 10 for retracting the piston 12, and such connection includes passages 80 and 78, a part of conduit 32, conduit 34, valve 36 (when valve member 96 is in its other position), and conduit 48, in the position in which the valve 36 is shown, the connection just described is obstructed. However, on the up stroke of the press ram, a link 90 having a pin and slot connection at one end with an arm 92 movable with the press ram 64 and a pivoted connection at its other end with an arm 94 fixed to rotary valve member 96, is effective for shifting the rotary valve member 96 to its other position so that the passage 98 in the valve member 96 interconnects the conduits 34 and 48 rather than the conduits 34 and 38. As shown, passage 100 in rotary valve member 96 interconnects conduits 48 and 50, but when the valve member 96 is shifted to its other position upon the upstroke of the press, the passage 10d will interconnect the conduits 38 and 50, thereby porting the cylinder 10 on one side of the piston 12 to the tank 2i) through the conduit 33, the passage 100, the passage 50, passage 52, and the conduit 24, while the other end of the cylinder 10 is connected to the cylinder 70 of the pump 72 through the conduit 48, the valve passage 98, the conduit 34, part of the conduit 32, the passage 78 and the passage 80, whereby hydraulic fluid discharged from the cylinder 70 is supplied to the piston rod side of the cylinder 10 to effect the retraction of the piston 12.

On the closing stroke of the press ram 64, the pin 101 on the arm 92 moves away from the end of the slot 1&2 in the link 90 and permits spring 104 reacting on arm 94 to shift the valve member 96 to the position shown so that hydraulic fluid from the tank is supplied through the fluid-flow connection 22 to the cylinder 10 for advancing the piston therein before the press closes. As the press opens, hydraulic fluid from the tank will be supplied to the cylinder 58 to recharge the same and thereby retract the piston 62. In addition, hydraulic fluid will also be supplied to the hydraulic cylinder 70 of the pump 72 for recharging the same and retracting the piston 82 when the air cylinder is ported to atmosphere as shown. As the press closes, the press ram 64 will eng ge the piston 62 and advance the same in cylinder 58 thereby substantially increasing the pressure of the hydraulic fluid on the high pressure side of the system and advancing the piston 12 through the final portion of its stroke. As previously indicated, the pressure relief valve 49 will open to release hydraulic fluid from the high pressure side of the system if the piston 12 reaches the end of its stroke before the press ram 64 reaches the bottom of its stroke.

On the upstroke of the press, the arm 92 will move the link 90 so as to shift the valve member 96 to its other position and at the same time air under pressure (for example. 100 lbs. per sq. in.) is supplied to the air cylinder 86 through the conduit 110 for reacting on the piston 112 in the air cylinder 86 so as to advance the piston 82 in the cylinder 70 for discharging hydraulic fluid from the cylinder 70 to the work cylinder 10 on the piston rod side thereof for retracting the piston 12. A rotary valve 114 is arranged in the air pressure line and is connected by a link 116 through a pin and slot connection to an arm 118 movable with the press ram 64 so that on the upstroke of the press valve 114 will be shifted counterclockwise to its other position Whereby air under pressure will be supplied to the air cylinder of the pump 72 for actuating the same. On the downstroke of the press ram, the downward movement of the arm 138 permits spring 120 to react on the actuating arm 122 of the valve 114 for biasing the same to its position as shown whereby the valve passage 124 ports air cylinder as to atmosphere and permits recharging of the cylinder 70 with hydraulic fluid.

Thus the air control valve 114 is shifted from one position to another so that the hydraulic fluid discharged by pump 72 will operate to retract the piston 12 of the work cylinder 10 and the rod 14, and the die parts connected therewith. The effective area of the air piston 112 is many times that of the hydraulic piston 82 so that the pump 72 is etfective to impose a substantially higher pressure (five to ten times) on the hydraulic fluid in the system than that imposed thereon by the pressure to which the hydraulic fluid in the tank 20 is subjected. As the effective area of the piston 12 on the piston rod side thereof is less than the effective area on the opposite side of such piston, and as the piston 12 is retracted against the pressure in the tank 20, it will be understood that the pressure required to effect the retraction of the piston 12 must be higher than that obtaining in the tank 20, and such higher pressure is provided by the pump 72 which functions as a booster for temporarily increasing the pressure on the high pressure side of the system to eflfect retraction of the piston 12.

From the foregoing it follows that the pressure obtaining in the tank 20 is effective for advancing the piston 12 of the work cylinder 10 through the initial portion of the work stroke thereof; that the hydraulic pressure cylinder 58 actuated by the press ram 64 upon the closing thereof supplies high pressure hydraulic fluid to the work cylinder to advance the piston through the final portion of the work stroke thereof; and that the pump 72 is emnloyed to effect the rapid retraction of the piston 12 of the Work cylinder. Work cylinder 10 may be located remote from the press and on any desired plane or axis.

FIG. 2 discloses a modification of FIG. 1 in which the link 116 for operating the air valve 114 is replaced by a solenoid-operated link 200 the lower end of which is pivotally connected with the end of the valve operating arm 122 for shifting the valve 114 to its other position when the solenoid is energized. The solenoid indicated generally at 202 is normally de-energized so that the valve 114 is biased to the position as shown in FIG. 1 in which the air cylinder 86 of the booster 72 is ported to atmosphere.

The solenoid 202 is included in an electric circuit which includes a normally open switch 204 arranged to be momentarily closed by rotary cams 206 and 208 mounted on a rotary shaft 210. The shaft 210 may be the crankshaft of the press or driven in timed. relation therewith in any suitable manner. The cams 206 and 208 are spaced from each other and arranged upon rotation of the shaft 210 to successively engage the movable contact 212 of the switch 204 for momentarily closing the circuit through the solenoid 202 for energizing the same, thereby to momentarily position the air control valve 114 so as to admit air under pressure to the air cylinder 86 of the booster 72 for energizing the same. The cams 206 and 208 may be adjustably mounted on a bushing 214 which rotates with the shaft 210. The control arrangement illustrated in FIG. 2 makes it possible to energize or actuate the booster 72 on the downstroke of the press before the ram 6 4 advances the pressure piston 62 so that the hydraulic fluid discharged from the booster cylinder 70 will be supplied to the work cylinder 10 with the valve 36 positioned as illustrated in FIG. 1 for rapidly advancing the piston 12 in the Work cylinder 10 before the closing of the press. Thus the fluid so discharged from the hydraulic cylinder 70 of the booster 72 may be employed to advance the piston 12 during the initial part of the work stroke if the pressure prevailing in the tank 20 is inadequate for this purpose, or to accelerate the advancing stroke of the piston 12.

The cams 206 and 208 may be adjustably mounted on the bushing 214 so that the cam 2% will close the sole noid circuit to actuate the air valve 114 so as to energize the booster 72 during the closing stroke of the press, while the cam 208 may be positioned so as to energize the booster 72 on the opening of the press whereby the hydraulic fluid discharged by the hydraulic cylinder 70 of the booster 72 will be effective for retracting the piston 12 when the valve 36 is in its other position as previously described in connection with the modification of FIG. 1. It will be understood that the cams 206 and 208 may be adjusted so as to close the solenoid circuit at any desired part of the cycle of the press, and that of course only one cam may be used to actuate the booster 72 at any desired part of the cycle. It will also be appreciated that the switch 204 may be closed manually when the press is not operating for using the fluid discharged by the booster 72 for advancing and/ or retracting the piston 12 in the work cylinder 10, and this of course will entail manual shifting of the valve 36 between its two positions.

In the modification illustrated in FIG. 3 the system is similiar to that of FIG. 1 and differs therefrom in that the valve 36 has been replaced by a specifically different rotary valve 300 which alternately connects the work cylinder with either the booster 72 or the high pressure cylinder 58. The controls as illustrated and described in connection with FIG. 1 or FIG. 2 may be employed for the system as illustrated in FIG. 3 wherein like parts carry the same reference characters as employed in FIG. 1.

As shown in FIG. 3, the press ram 64 has engaged the piston 62 and is advancing the same in the cylinder 58 so as to displace fluid therefrom under nigh pressure into the connection 302 which as shown extends through the valve 300 to the cylinder 10 to advance the piston 12 through the final portion of the work stroke. A connection indicated generally at 304 extends from the tank 20 to the hydraulic cylinder 70 of the booster for recharging the cylinder 70 with hydraulic fluid under the pressure prevailing in the tank 20. The end of the cylinder 12 on the piston rod side thereof is connected through conduit 306 and the valve 300 to the connection 304 whereby fluid displaced from the cylinder 10 as the piston 12 advances therein is returned to the tank 20. As shown in FIG. 3, the valve 300 is set so that the hydraulic cylinder 70 of the booster '72 is not in communication with the cylinder 10, and any hydraulic fluid discharged by the cylinder 70 at such time will be returned to tank 20 through conduit 312, valve 300, and conduits 313 and 304. However, as the press opens the link 90 will shift the rotary valve member 310 clockwise to its other position so as to break the connection 302 between the cylinder 58 and the cylinder 10 and to connect the hydraulic cylinder 70 with the cylinder 10 through the communication 312 for supplying hydraulic fluid under pressure to the piston rod side of the cylinder 10 for retracting the piston 12.

The connection 312 includes the conduit 314, the passage 316 in the rotary valve member 310, and the conduit 306. In such other position of valve 300 the other end of the cylinder 10 will be in communication with the tank 20 through the communication 320 which includes the conduit 322, the passage 324 in the valve member 310, and the passage 326 which communicates past check valve 54 with the communication 304.

Thus in the system of FIG. 3 and using the controls as illustrated in FIG. 1, the piston 12 will be advanced through the initial portion of the work stroke by hydraulic fluid from the tank under the pressure prevailing therein as in FIG. 1, and through the final portion of the Work stroke by the hydraulic fluid discharged from the high pressure cylinder 58 upon the closing of the press ram. Upon the opening of the press ram the valve member 310 will be shifted to its other position whereby the hydraulic fluid discharged from the booster cylinder 70 will be effective for retracting the piston 12. Using the control system illustrated in FIG. 2 with the system of FIG. 3, the booster 72 will be actuated during both the closing and the opening strokes of the press it both cams 206 and 208 are used, whereas if only one of such cams is used the booster 72 may be actuated only on the opening strokeof the press. If both cams 206 and 208 are used, the cam 206 should be set so as to energize the booster when the valve member 310 is in its dotted line position so that the discharge from the booster cylinder 70 on the closing stroke of the press may be employed for advancing or accelerating the advance of the piston 12.

In the system of FIG. 4, which is a modification of that shown in FIGS. 1 and 3, the booster 72 has been eliminated and air pressure is applied to the piston 12 of the work cylinder 10 for retracting the same. In other respects the system is the same as that illustrated in FIG. 1 wherein air under pressure in the tank 20 is employed to advance the piston 12 through the initial portion of the work stroke and the hydraulic fluid displaced from the high pressure cylinder 58 upon the closing of the press ram 64 is employed to advance the piston 12 through the final portion of the stroke. Instead of using the valve 36 as illustrated in FIG. 1, a rotary valve indi cated generally at 400 is employed for connecting one end of the cylinder 10 to the tank 20 for returning to the tank the hydraulic fluid displaced from the work cylinder 10 during the retractile stroke of the piston 12.

The valve 400 includes a rotary valve member 402 having cross passages 404 and 406. An arm 408 connected to the rotary valve member 402 has a pin and slot connection with a link which in turn has a pin and slot connection with an arm 92 movable with the press ram 64 whereby the rotary valve member 402 is positioned as shown during the closing of the press so that the high pressure fluid discharge from the cylinder 58 may be supplied to the work cylinder 10 for advancing the piston 12 therein during the final portion of the work stroke. It will be understood that before the piston 62 tive to shift the rotary valve member 402 counterclockwise to its other position so that the hydraulic fluid from the cylinder 10 displaced therefrom by the retraction of the piston 12 may be returned to the tank 20 through the by-pass conduit 412, which at such time communicates with one end of the cross passage 404.

An air line 414 is connected to the cylinder 10 on the piston rod side thereof and at its other end to an air control valve 416 which in the position shown ports the air side of the cylinder 10 to atmosphere. The link 00 is connected by a pin and slot connection to an actuating arm 418 of the rotary valve member 420 of the valve 416 so that on the opening of the press the valve member 420 will be shifted in a clockwise direction to interconnect the air line 414 with the air pressure line 422 whereby air under pressure will be supplied to the air pressure side of the cylinder 10 to regulate the same. Since the effective area of the piston 12 on the piston rod side thereof is less than the efiective area on the opposite side, it will be appreciated that the air pressure supplied to the air pressure side of the cylinder 10 must be sufliciently higher than the pressure prevailing in the tank 20 so as to retract the piston 12 against the pressure prevailing in the tank 20.

In the systems of FIGS. 1, 2 and 3 the air pressure source connected to the tank 20 may be the same as that supplied to the booster 72 for energizing the latter, whereas in the system of FIG. 4 the air pressure supplied through the line 422 must be substantially higher than that supplied to the tank 20 in view of the difference in area on the opposite sides of the piston 12. The boosters 72 of the systems of FIGS. 1, 2 and 3 provide the additional pressure required to provide a positive stripping action for return of the slide or punch, whereas in the system of FIG. 4 the high pressure air supplied through the line 422 provides the extra pressure needed for this purpose.

While I have illustrated and described preferred embodiments of my invention, it is understood that these are capable of modification, and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of suchchanges and alterations as fall within the purview of the following claims. 7

I claim: I iv 1. In combination with a press ram, a hydraulic system for utilizing the press ram to efiect the working stroke of a tool, said system including a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to eifect the working stroke of a tool, a. fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid under pressure is supplied from said tank to said cylinder to react on the piston therein, a hydraulic pressure cylinder actuated by the press ram upon the closing thereof and connected to said one end of said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank to advance said piston therein through the work stroke thereof, a reciprocating piston pump supplied with hydraulic fluid under pressure from said tank and having a connection with the other end of said work cylinder for supplying hydraulic fluid thereto to retract said piston, valve controlled means alternately connecting said ends of said work cylinder to said tank for returning to said tank hydraulic fluid displaced from said work cylinder by the piston therein, and means controlled in accordance with movement of the press ram for actuat ingsaid pump to effect the supply of fluid therefrom to said work cylinder.

2. Apparatus according to claim 1 wherein said means for actuating said pump comprises an air pressure operated power cylinder and an air valve operated in accordance with movement of the press rarn for admitting air under pressure to saidpower cylinder and releasing air under pressure therefrom.

3. Apparatus'according to claim 1 wherein said means for actuating said pump comprises an air pressure operated power cylinder, an air valve operated in accordance with movement of the press ram for admitting air under pressure to said power cylinder and releasing air under pressure therefrom, and a mechanical linkage between said air valve and said press ram whereby said I air valve is operated by movement of the press ram.

4. Apparatus according to claim 1 wherein said means for actuating said pump'comprises an air pressure operated power cylinder, and a solenoid operated air valve operated in accordance with movement of the press ram. for admitting air under pressure to said power cylinder and releasing air under pressure therefrom.

5. Apparatus according to claim 1 including provisions for operating said valve controlled means in accordance with movement of the press ram.

6 In combination with a press ram, a hydraulic system for utilizing the press ram to effect the final portion of the working stroke of a tool, said system including a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to effect the working stroke of a tool, a fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid under pressure is supplied from said tank to said cylinder for advancing the piston therein, a hydraulic pressure cylinder actuated by the press ram upon the power stroke thereof and connected to said end of said cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank to advance said piston through the final portion of the work stroke thereof, an air pressure operated booster supplied with hydraulic fluid from said tank and connected to the other end of said work cylinder for supplying hydraulic fluid thereto to retract said piston, means connecting the ends of said work cylinder to said tank for returning to said tank hydraulic fluid displaced from said work cylinder by the piston therein, and means controlled by the press rarn on the upstroke thereof for supplying air under pressure to said air pressure operated booster to effect the supply of fluid therefrom to said work cylinder.

7. In combination with a press ram, a hydraulic system for utilizing the closing of the press ram to effect the final portion of the working stroke of a tool, said system including a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to effect the working stroke of a tool, a fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid is supplied under pressure from said tank to said Work cylinder to react on the piston therein for advancing said piston, a hydraulic pressure cylinder actuated by the press ram on the power stroke thereof and connected to said one end of said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank to advance said piston through the final portion of the work stroke thereof, a pump supplied with hydraulic fluid from said tank and having a connection with the other end of said Work cylinder for supplying hydraulic fluid thereto to retract said piston, valve controlled means alternately connecting said ends of said work cylinder to said tank for returning hydraulic fluid displaced from said work cylinder to said tank, and means controlled in accordance with movement of the press ram for actuating said pump to effect the supply of fluid therefrom to said work cylinder.

8. Apparatus according to claim 7 wherein said pump has a connection with said one end of said work cylinder for supplying fluid thereto to advance the piston on the work stroke thereof.

9. In combination with a press ram, a hydraulic system for utilizing the closing of the press ram to eflect the final portion of the working stroke of a tool, said system including a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to effect the working stroke of a tool, a first fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid is supplied from said tank to said cylinder to advance the piston therein through the initial portion of the Work stroke thereof, a hydraulic pressure cylinder actuated by the press ram upon the closing thereof and connected to said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank to advance said piston through the final portion of the work stroke thereof, a second fluid flow connection from said tank to said hydraulic press cylinder through which hydraulic fluid is supplied from said tank to said hydraulic pressure cylinder, a reciprocating piston pump connected to said tank to be supplied with hydraulic fluid therefrom and connected to the other end of said work cyhnder for supplying hydraulic fluid thereto on the working stroke of the pump to retract said piston, air pressure operated means for reciprocating said piston pump, valve controlled means alternately connecting said ends of said work cylinder to said tank for returning hydraulic fluid displaced from said work cylinder to said tank, and means controlled by the press ram for supplying air under pressure to the operating means for said air pressure operated pump for effecting the working stroke thereof so as to supply fluid therefrom to said work cylinder.

10. Apparatus as set forth in claim 9 wherein said valve controlled means includes a valve shiftable between one position connecting said other end of said work cy1in der to said tank when said one end of said work cylinder is being supplied with hydraulic fluid to advance the piston therein and a second position connecting said one end of said work cylinder to said tank when said other end of said work cylinder is being supplied with hydraulic fluid from said pump to retract the piston therein, and linkage interconnecting said valve and press ram for shifting said valve from one of its positions to another upon movement of said press ram.

11. In combination with a press ram, a hydraulic sys tem for utilizing the closing of the press ram to effect the final portion of the working stroke of a tool, said system including a hydraulic work cylinder having a piston therein arranged to be advanced to effect the working stroke of a tool, pump operating means, a booster pump including a hydraulic cylinder having a piston therein arranged to be advanced when air under pressure is supplied to said pump operating means, a hydraulic pressure cylinder having a piston therein arranged to be advanced by the press ram upon the closing thereof, a tank of hydraulic fluid under pressure, fluid flow connections from said tank to said cylinders whereby hydraulic fluid is supplied from said tank to said cylinders to advance the piston in said work cylinder and to retract the pistons in said pump and pressure cylinders, a fluid flow connection between said pressure cylinder and work cylinder whereby hydraulic fluid discharged from said pressure cylinder upon the advance of the piston therein is supplied to said work cylinder to advance the piston therein through the final portion of the work stroke thereof, a fluid flow connection between said pump cylinder and said work cylinder whereby hydraulic fluid discharged from said pump cylinder by the advance of the piston therein is supplied to said work cylinder to effect the retraction of the piston therein, valve controlled means alternately connecting the ends of said work cylinder to said tank for returning to said tank hydraulic fluid displaced from said work cylinder by the reciprocation of the piston therein, means controlled by the press ram on the upstroke thereof for supplying air under pressure to said operating means for said pump, and linkage actuated by movement of the press ram and connected to said valve controlled means for alternating the valve thereof.

12. Apparatus according to claim 11 including valve means controlled by movement of the press ram, in the connections between said work cylinder and said pressure and pump cylinders, respectively, whereby said pressure and pump cylinders are alternately connected to said work cylinder.

13. In combination with a press ram, a hydraulic system for utilizing the closing of the press ram to efliect the final portion of the working stroke of a tool, said system including a hydraulic work cylinder having a piston therein arranged to be advanced to effect the working stroke of a tool, a booster pump including a, hydraulic cylinder having a piston therein arranged to be advanced when said pump is actuated, a hydraulic pressure cylinder having a piston therein arranged to be advanced by the press ram upon the closing thereof, a tank of hydraulic fluid under pressure, fluid flow connections from said tank to said cylinders whereby hydraulic fluid is supplied from said tank to said cylinders to advance the piston in said work cylinder and to retract the pistons in said pump and pressure cylinders, a fluid flow connection between said pressure cylinder and work cylinder whereby hydraulic fluid discharged from said pressure cylinder upon the advance of the piston therein is supplied to said work cylinder to advance the piston therein through the final portion of the work stroke thereof, a fluid flow connection between said pump cylinder and said work cylinder whereby hydraulic fluid discharged from said pump cylinder by the advance of the piston therein is supplied to said work cylinder to efiect the retraction of the piston therein, means connecting the ends of said Work cylinder to said tank for returning hydraulic fluid displaced from said work cylinder to said tank, and means controlled by the 10 press ram on the upstroke thereof for actuating said booster pump.

14. In combination with a press ram, a hydraulic system for utilizing the press ram to effect the final portion of the working stroke of a tool, said system including a hydraulic work cylinder having a piston therein arranged to be advanced to eflect the working stroke of a tool, an air pressure operated pump including air pressure actuated pump operating means and a hydraulic cylinder having a piston therein arranged to be advanced when air under pressure is supplied to said pump operating means, a hydraulic pressure cylinder having a piston therein arranged to be advanced by the press ram upon the closing thereof, a tank of hydraulic fluid under pressure, fluid flow connections from said tank to said cylinders whereby hydraulic fluid is supplied from said tank to said cylinders, a fluid flow connection between said pressure cylinder and work cylinder whereby hydraulic fluid discharged from said pressure cylinder upon the closing of the press ram is supplied to said Work cylinder to advance the piston therein, a fluid flow connection between said pump cylinder and said work cylinder whereby hydraulic fluid discharged from said pump cylinder by the advance or the piston therein is supplied to said work cylinder to eflect the retraction of the piston therein, means connecting the ends of said work cylinder to said tank for returning hydraulic fluid displaced from said work cylinder to said tank, and means for supplying air under pressure to said pump operating means.

15. In combination with a press ram, a hydraulic system for utilizing the press ram to eitect the working stroke of a tool, said system including a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to efl'ect the working stroke of a tool, said ram and piston being mechanically disconnected, a fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid is supplied from said tank to said cylinder to react on the piston therein for advancing said piston independent of ram movement through a portion of the work stroke of said piston, a hydraulic pressure cylinder actuated by the press ram upon the closing thereof and connected to said one end of said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank to advance said piston through the final portion of the work stroke thereof, means for supplying fluid to the other end of said work cylinder to retract said piston, valve means alternately porting said ends of said work cylinder for discharging therefrom fluid displaced from said work cylinder by the piston therein, and means controlled by movement of the press ram for controlling said valve means.

16. Apparatus according to claim 15 wherein said means for supplying fluid to the other end of said work cylinder to retract said piston comprises an air pressure operated hydraulic pump supplied with hydraulic fluid from said tank.

17. Apparatus according to claim 15 wherein said fluid supplied to the other end of said work cylinder to retract said piston is air under pressure.

18. In combination with a press ram, a hydraulic system for utilizing the closing of the press ram to eifect the working stroke of a tool, said system including a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to effect the working stroke of a tool, said ram and piston being mechanically disconnected, a fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid is supplied from said tank to said cylinder to react on the piston therein for advancing said piston independent of ram movement, a hydraulic pressure cylinder actuated by the press ram upon the closing thereof and connected to said one end of said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank .to advance said piston through the work stroke thereof,

a second connection between said hydraulic pressure cylinder and said tank through which hydraulic fluid under pressure is supplied from said tank to said hydraulic pressure cylinder, at pressure relief valve in said second connection, means for supplying pressure fluid to the other end of said Work cylinder to react on the piston therein for retracting the same, said last-named means being operable in response to opening movement of the press ram, and a connection between said one end of said work cylinder and said tank through which hydraulic fluid is returned from said work cylinder to said tank upon retraction of the piston in said Work cylinder.

19. In combination with a press ram, a hydraulic system for utilizing the press ram to effect the working stroke of a tool, said system including a work cylinder having a piston therein operable upon the advance thereof to etfect the working stroke of a tool, said ram and piston being mechanically disconnected, a tank of hydraulic fluid under pressure connected to said system for supplying hydraulic fluid thereto, a hydraulic pressure cylinder disposed so as to be actuated by the press ram upon the closing thereof and connected to said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank so as to advance said piston through the work stroke thereof, and means for retracting said piston upon the upstroke of the press ram.

20. In combination with a press having a ram and a bolster, a hydraulic system for utilizing the press ram to effect the working stroke of a tool, said system including a .work cylinder having a piston therein operable upon the advance thereof to effect the Working stroke of a tool, said ram and piston being mechanically disconnected, a tank of hydraulic fluid under pressure connected to said system for supplying hydraulic fluid thereto, a hydraulic pressure cylinder mounted on said bolster so as to be actuated by the press ram upon the closing thereof and connected to said work cylinder for supplying hydraulic fluid thereto under a pressure substantially higher than that provided by said tank so as to advance said piston through the Work stroke thereof, and means controlled by movement of the press ram for supplying fluid under pressure to said work cylinder for retracting said piston.

21. A hydraulic system for effecting the Working and 'retraction strokes of a tool comprising a tank of hydraulic fluid under pressure, a Work cylinder having a piston therein operable upon the advance thereof to effect the working stroke of a tool, a first one-way fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid is supplied from said tank to said cylinder to advance the piston therein, a hydraulic pressure cylinder connected to said work cylinder for supplying hydraulic fluid thereto under a pressure substantially hi her than that provided by said tank to advance said piston through the final portion of the work stroke thereof, a reciprocating piston pump connected to said tank to be supplied with hydraulic iluid therefrom and connected to the other end of said work cylinder for supplying hydraulic fluid thereto on the working stroke of the pump to retract said piston, air pressure operated means for said piston pump, valve controlled means alternately connecting said ends of said work cylinder to said tank for returning hydraulic fluid displaced from said work cylinder to said tank, and means for supplying air under pressure to the operating means for said pump for effecting the working stroke thereof so as to supply hydraulic fluid therefrom to said work cylinder.

22. A hydraulic system for effecting the Working and retraction strokes of a tool comprising a tank of hydraulic fluid under pressure, a work cylinder having a piston therein operable upon the advance thereof to effect the working stroke of a tool, a first one-way fluid flow connection from said tank to one end of said cylinder through which hydraulic fluid is supplied from said tank to said cylinder to advance the piston therein, a hydraulic pressure cylinder connected to said Work cylinder for supplying hydraulic fluid thereto under a pressure substan tially higher than that provided by said tank to advance said piston through the final portion of the Work stroke thereof, a pump connected to said tank to be supplied with hydraulic fluid therefrom and connected to the other end of said Work cylinder for supplying hydraulic fluid thereto on the working stroke of the pump to retract said piston, air pressure operated means for actuating said pump, valve controlled means alternately connecting said ends of said work cylinder to said tank for returning hydraulic fluid displaced from said work cylinder to said tank, and means for supplying air under pressure to the operating means for said pump for eifecting the working stroke thereof so as to supply hydraulic fluid therefrom to said work cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,332,340 Home Mar. 2, 1920 2,110,393 Edwards Mar. 8, 1938 2,403,912 Doll Euly 16, 1946 2,573,993 Sedgwick Nov. 6, l 

